The novel follows the lives of the Holbrook family, who are struggling to survive during the Great Depression. The family consists of Anna and Jim, their children Mazie, Emily, Ben, Janey, Sam, and Evie, and various other family members and acquaintances. The story focuses on the family's poverty, illness, and social injustice, and their attempts to survive and find happiness in the face of adversity. Other characters include Mazie's boyfriend and a young boy named Shim, who is Mazie's friend. The novel begins in a small Wyoming mining town, where Jim Holbrook works in the coal mine. As the narrative progresses, the reader discovers that Jim drinks heavily and beats Anna and their children. Mazie follows Jim into town one evening and is nearly thrown down a mineshaft by the deranged miner, Sheen McEvoy. Mazie is saved by the night watchman, and instead McEvoy falls down the shaft to his death. Mazie immediately develops a fever, and the Holbrooks make plans to move east in the spring. Anna takes on a variety of short-term employment to financially prepare for the move. Jim is involved in a mine explosion, attributed to the carelessness of the new fire boss, and goes missing for five days. When Jim returns, it is with a firm resolve to remove his family from the town.
In the spring, the Holbrooks leave the mining town, traveling across Nebraska and South Dakota, where their wagon is briefly immobilized by a storm. At their South Dakota tenant farm, the scene is pastoral and the Holbrooks are initially optimistic about the farm's prospects. For the first time, the family is healthy and well-fed, and Mazie and Will begin attending school. Mazie begins to take an interest in education and befriends the learned Old Man Caldwell next door, who passes on some books to Mazie when he dies, though Jim promptly sells them. As the winter approaches, Jim realizes that after a year of working the land, the family remains in debt. With the arrival of winter, the Holbrooks no longer have enough food. Anna becomes pregnant and ill, and after a marital dispute, Jim leaves the family, returning after ten days.
After the birth of Bess in the following March, the family leaves the farm and moves to Omaha, Nebraska. They take up residence in a city slum near a slaughterhouse. The smell from the slaughterhouse makes the children ill and Anna is no longer able to control them at home. Mazie becomes dreamy and detached, fantasizing about the farm as an escape from the horrors of the city. Jim gets a job in the sewers, and he and Anna are unable to support their family. Anna suffers a miscarriage and is bedridden for several days. When she regains mobility, Anna begins taking in laundry to supplement Jim's income, though Jim explicitly disapproves. Jim gets a job at the slaughterhouse, where he earns a little more money, and he buys fireworks for the family on the Fourth of July to celebrate. When she is excluded from the celebration, Mazie becomes acutely conscious of the social and political implications of her gender. During a heat wave, Anna continues to work alone, canning fruits to feed the family through the winter, while the children run the streets and scavenge in the dump. The novel ends in the Holbrook apartment, with Anna singing to Ben. Bess enthusiastically bangs a jar lid against the floor, and the family listens to the radio together for the first time.
